had passed

would pass

would have passed

would allow

had allowed

would have allowed

would have got

had got

would has

hadn't left

wouldn't have left

didn't leave

wouldn't have driven/ hadn't had

had driven/ would have had

hadn't driven /wouldn't have had

Her grandfather died last week. If she had known that he was ill, she would have visited him more often.

Her grandfather died last week. If she knew that he were ill, she would have visited him more often.

If I were you, I would apologise.

If I had been you, I would have apologised.

a probable situation.

hypothetical ,imaginary situations.

a regret about a past situation which is impossible to change.

I would help him.

I would have helped him.

I had helped him.

took / wouldn't be

would have taken/ hadn't been

had taken/ wouldn't have been